In modern smart grids electric power quality problems such as flicker (voltage fluctuation), is a major concern of electric companies and industrial consumers.Identification of flicker sources is an important stage in flicker reduction process. For equal fluctuation frequency of flicker sources, since frequency character of the flicker sources cannot be used for identifying the sources, detection of coupling points of these sources is not an easy task especially in non-radialnetworks. In this paper the power system with arbitrary flicker sources is assumed and simulated to generate a set of training data. Then two methods based on K-means clustering algorithm and correlation coefficient are introduced to identify locations of the flicker sources in a non-radial power system. By using the proposed methods, locations of the flicker sources with similar fluctuation frequency in non-radial power system are determined. Voltage envelope is extracted by Enhanced Phase- Locked Loop (EPLL) which acts as a nonlinear adaptive filter, and then the amplitude of flicker tone is used as a flicker index.In a typical test system, several simulations are conducted. The simulation results show the performance of the proposed method is very promising and flicker sources can be detected tolerably